Fluid pressure tool



June 6, 1933. G. M. NELL FLUID PRESSURE TOOL Filed March .12, 1929 Lig-l LII 2 Sheets-Sheet l June 6, 1933. G. M. NELL FLUID PRESSURE TooL Filed March l2, 1929 2 SheetsSheet 2 m d WN e `V im U G A TT ORNEY.

Patented June 6, 1933 UNITED STATES PATENToFFicE eUsTAvE M. NELL, or DETROIT, MICHIGAN, AssIeNoR To oIIIoAGo `IunanrMaTIe` TooL y COMPANY, or NEW YORK, N; Y., A CORPORATION or NEW JERSEY y normal to thedirectionrof tripping. An-` `FLUID PRESSURE TooI.

Application le. March 12, 1929. Serial No. 346,282.

This invention relates to Huid` pressure `motors and to the control and distribution of the motive iiuid in the same. More `particularly it concerns percussive tools and machines which utilize for the controlling valve ayhollow cylindrical member.

y Oneobject of the invention is to so balance the forceson such a valve as to cause it to move in a straight line thereby to minimize motive fluid losses and to prevent thrusts on the valve which are moreor less other object is to provide a generally rugged valve assembly whichy is readily assembled and disassembled .and to avoid parts which are easily loosened, broken, or lo-st such as bolts and nuts. Another object is to hold thevalve inone position for hole cleaning.

Other objects will be apparent from the de-` tailed description which follows. In order to illustrate the invention and the manner of its operation and use, one con-V crete embodiment thereof with certain slightl drawings, in which:

modifications is shown in the accompanying y Fig. `1 is a vertical sectional View through `a pneumatic percussive drill;` y

Fig.l 2 is a fragmentary plan view-taken from the left side of Fig. 1;

Fig. 3 is a detail sectional view on an enlarged scale substantially on the line 83 of Fig.`1 but showing thevalve shifted to its lower position;

Fig. 4 is a detail perspective view of the valve parts in separated arrangement on the scale of Fig. 3; Y y

Fig. yshows the valve case sectioned adjacent its further end substantially on the line 5 5 of Fignt; i

Fig. 6 is a top plan view of the valve case shownin"` Fig. 1 with the lid removed; y

Fig. is a sectional View through a valve case.l similar to thatshown in Fig. 1` but taken in a plane at right angles tothe same;

Fig. 8 is a fragmentarysectional view of Va-portion `of `the hammer cylinder 'shown in- 8 showing a modification conforming sub-` stantially to that shown inFig, 7.

The embodiment of the Vinvention shown in Fig. 1 is a light pneumatic hand drill comprising essentially a cylinder 7 providing a piston chamber within which re- .p y `ciprocates a hammer piston 8 arranged to strike blows upon the shank of a hollow drill steel 9 supportedin a chuck 10 rotatably mounted in; the front head 11. Conventional rotation mechanism is provided comprising a rifle nut 12 secured in a recess in i piston 8 cooperating with a rilie bar 13 projecting from the back head or handle 14 of the drill. The rotative impulse imparted to piston 8 is transmitted to chuck 10 by fiutes or splines 8a on the piston extension. slidably engaging corresponding flutes or splines a on the chuck. Toward the end of its rear ward or non-working stroke, the grooves between the iiutes or splines 8a of the piston open into `the forward end of the piston chamber so that pressure fluid therein may escape to the bore of drill steel 9 and around the shank of the latter thereby forming a sort Vof auxiliary piston controlled exhaust in addition to the main exhaust ports 14: and

15. This auxiliary exhaust arrangement maybe utilized for hole cleaning as will be later described.

Motive Huid forreciprocating the piston reaches the rear of the piston chamber through a passage 16 and the forward end thereof through a passage 17 under control of a hollow cylindrical or tubular valve 18. The valve with its valve case is mounted in a bore 7m in the cylindertransverse to the axis of the drill and substantially on the centerline of the piston chamber so that passa es 16 and 17 leading to the piston cham er may be short and direct. The parts forming the valve chamber together with the valve are insertable through bore 7a and may be resiliently heldin place by a spring 19 which seats against an adapter member 20 to which the fluid pressure supply hose or conduit is attached. The pressure fluid enters the bore of valve 18 through an opening in valve cap 21 so that the interior of the valve is filled with motive fluid at all times. At either side of the open ends of valve .18, ports 22 lead to transverse grooves 23 which,

as indicated, are four in number, two being at each end of the slightly elongated valve chamber and at either side of and immediately adjacent ports 16a and 17a connecting with passages 1G and 17 respectively. It will thus be seen that valve-18 has live motive fluid both within and without and is thereby at least partially balanced. Its movement is cushioned against the thrust from the resultant pressure which holds it on its opposed seats, either over port 16al or over port 17a. In order to produce an increased balancing effect and to malte the valve more sensitive to pressure changes, annular reliefs are provided on each outside end of valve 18. These reliefs preferably take the form of grooves or reduced portions 18a and together with the valve chest grooves 23 provide for a constant pressure of live motive fluid on the corresponding portions of the valve tending to lift it off either seat. Such tendency is of course prevented by the preponderance of oppositely exerted motive fluid pressure due to the fact that the area of either passage 16 or 17 is open to atmosphere through the vents in the piston chamber until the latter are closed in alternation by piston 8.

Tith the tool in operation and the parts in the position shown in Fig. 1, the valve 18 has just moved to close port 16a and to open port 17a so that pressure fluid is passing through the latter to the forward end of the piston chamber to drive piston 8 rearwardly. As the piston closes exhaust ports 14, the air trapped in the rear end of the chamber while on the opposite piston chamber will be compressed and forced into passage 16 with the tendency first to balance the pressure at the portion of the valve face which covers this passage and then to move the valve in the directionV opposite to the va ve arrow. As the front edge of the piston uncovers exhaust ports 15 leading to atmosphere, the motive fluid pressure in the forward end of the chamber and in passage 17 will drop, thereby reducing the pressure on the portion ofthe valve chamber adjacent this passage, and when the sum of the pressures acting opposite to the direction of the valve arrow (F ig. l) predominate over those opposed thereto the valve will shift downwardly to the position shown in Fig. 3 closing port 17a. This will open port 16a and reverse the cycle of movement of the piston. i

The motive fluid supply through adapter 2O dis made large relative to the valve chest ports such as 22, so that the quantity of motive fluid around the outside face of the valve is restricted. Ports 2Q are small as compared with the ports 16a and 17a so as to produce a comparatively low pressure in the valve chamber towardV the side from which pressure fluid is passing to the piston duced or closed sidev there is an ample supply to maintain a higher relative pressure. This arrangement, together' with the fact that a tendency toward balancing of pressures is effected by having live motive fluid in contact with all portions of the inside of the valve and with certain opposed portions of its exterior (with the exception of that part which seals either port 16a or 17a) insures a rapid shifting of the valve at the proper instant.

The purpose and utility of the extensions 18a: will be apparent from the following eX- planation: Disregarding for the present the extension 18a., and referring to Fig. 1, the resultant of all fluid pressure forces acting on the larger diameter part of valve 18 is in a direction tending to hold the valve on its upper seat. This is principally due to the fact that the upper port 16a, being connected to atmosphere, exerts less pressure downwardly on the valve than the high pressure port 17m does upwardly. But even after the piston 8 has covered the vent openings 14 and has moved upwardly to just equalize the pressure in ports 16a and 17m, the large diameter part of the valve will not of its own accord move immediately to the lower seat, especially since its upper half has a less area exposed to Huid pressure than the lower half, thereby probably causing a tendency to stick to the upper seat. Consequently the effect would be to delay movement of the valve until there is port 16a.

It has been found by experiment that the valve will move more quickly ifthere is a constant force on the valve tending always to move it to the opposite seat. To this end, the ends of the valve are reduced at 18a7 thereby permitting access of the fluid to each part of the external surface of the reportions, to e-Xertv pressure in all radial directions, but unequally. Referring again to Fig. l, the downward pressure on portions 18a is substantially full line pressure, while the upward pressure is reduced due to the fact that the lowerhalf of eXtensions 18a are directly adjacent port 17a in which the fluid is flowing under somewhat reduced pressure. It might appear at first that because the lower and upper fluid channels surrounding the extensions 18a are in communication with each other, the pressure will be equalized. Such, however, is not the practical effect. In one embodiment of the invention which was actually constructed, the grooves which form reduced portionsl 18m are of a depth of the order of five one-thousandths of an inch and man times this in width, say one-eighth inch, so that in a peripheral way a very large shifting surface or area is provided as compared to a small cross-sectional area cut away by the groove. @This small' cross-sectional area a preponderance of fluid pressure in the upper llt) A Ul

in conjunction with the valve guides, materially retards egress of high pressure motive fluid from the closed side ofthevalve to the open side. The open side is freely exposed to lowering of pressure at this time. This difference in pressure aids materially in shifting the valve quickly and forcibly.

The valve chest may be variously formed. For example, as shown in Fig. 8 the valve chest proper is formed entirely by cylinder 7 and a separate lid 21aI alone is provided for holding valve 18 in place. In Figs.` 1

. and 3-6 the valve chest is formed as a separate element- 24 which permits renewal when the same becomes worn. Figs. 7 and 9 show a three part valve chest comprising an inner lid 25, a central chest or part 24a, and an outer lid 21. j j To utilize the previously mentioned auxiliary exhaust (formed by the projection of the grooves of the piston extension into the forward piston chamber when piston S is retracted) for hole cleaning, means are provided for positively retaining valve 18 in the position shown in Fig. 1. For this purpose a blowing stem or member 26 is arranged to be forcibly pushed inwardly in passage 17 in the direction of the arrow thereon to Vengage the valve and to hold it in the position shown. The piston will then stay in a rearward position not uncovering orljust partially uncovering exhaust ports 15 so that a substantial quantity of pressure fluid will pass in a strong constant stream through port 17 a, passage 17, along the` grooves between the flutes 8m of the piston and into the open bore of steel 9 to blow the cuttings out of the hole lwhich is being drilled. When the operator releases his pressure upon blowing plunger 26, the motor will resume its normal operation.

`From the above it will be apparent that the admission of pressure fluid directly into the hollow bore of the valve and fromboth endsof the latter to the exterior surface of the latter permits a general balancing of the valve and avoidsiunbalanced thrusts on the latter other than in the desired valve throwing direction. Such balancing aids in a definite fand rapid throwing of the valve in a straightline and minimizes unnecessary wear. The construction is such that ready assembly and disassembly of the valve parts is possible independently of the rest of the machine and avoids the use of parts which become loose or lost, It provides a generally simple and rugged design which is essential in tools of this type.

While preferred forms of the invention have been herein shown and described, it is to be understood that the invention is not intended to be limited to the specific details thereof buttoY cover all changes, modifications, and adaptations within the scope of r the appended claims.

` I claim as myinvention: i

1. A fluid pressure tool having a cylinder providing a piston chamber, a piston reciprocable therein, said cylinder having a bore transverse to the axis of the sameA and passages leading therefrom to the opposite ends of said piston chamber, animperforate tubular valveinsertedinto said bore for controlling said passages, a. perforated flid inserted in said bore to form one end of the valve chamber, means holding said lid in place, a conduit connection to said bore for admitting pressure fluid through said lid into the interior of said valve, and means including perforations in said lid for admitting a portion of the pressure fluid to the valve chamber on the exterior of said valve.

2. A fluid pressure tool having a cylinder providing a piston chamber, a piston reciprocable therein, said cylinder having a bore transverse to the axis of the same and passages leading therefrom to the opposite ends of said piston chamber, an imperforate tubular valve inserted into said bore for controlling said passages, a perforated lid inserted in said bore to form one end of the valve chamber, resilient means holding said lid in place, a conduit connection to said bore for admitting pressure fluid through said lid into the interior of said valve, said lid having ports of restricted size for admitting a portion of the pressure fluid to the valve chamber on the exterior of said valve.

3. In a fluid pressure motor, in combination, an imperforate tubular valve having` annular reduced portions on its exterior at both ends to provide relief areas, a valve chest providing a slightly elongate chamber for said valve to permit limited rectilinear movement of the latter, said chest havingports substantially centrally of the ends of said elongated chamber for control by the Vunreduced portion of said valve, means for admitting pressure fluid into the central bore of said valve, andmeans beyond the open ends of said valve for conducting pressure fluid to the exterior of the ends of said chamber for control bysaid` valve, means for admitting pressure fluid into the central bore of said valve, means beyond the open ends of said `valve for conducting pressure fluid to the exterior of the i same, and means providing annular relief areas on the exterior of said valve adjacent 'l the ends thereof and beyond the portions thereof which control said ports.

5. An automatic control valve` for a/fluid March 1929.

' GUSTAVE M. NELL. 

